Packings laboratory size

Plate-and-Frame Tests These tests should be conducted if the use of a filter press in the plant is anticipated at least a few confirming tests are advisable after preliminary leaf tests, unless the slurry is very rapidly filtering. A laboratory-size filter press consisting of two plates and a single frame may be used. It will permit the observation of solids-settling, cake-packing, and washing behavior, which may be quite different for a frame than for a leaf. 

Methods for calculating the limiting velocity for plate colunms of laboratory size have, as far as the author is aware, not been published. The formulae valid for industrial columns prove to be inapplicable to small-scale apparatus. Experience shows that plate columns can be submitted to only about one third of the load that can be applied to packed colunms of the same diameter this is due to the resistance resulting from (a) the liquid present on the plates and (b) the restrictions in the vapour passages. 

Drying of NaCl solution and alumina suspension was investigated [30] in laboratory-size SBD inert packing. Experiments have been carried out in a cylindrical chamber 150 mm in diameter with conical base and an air inlet of 20 mm. The inert particles were mainly glass and plastic beads of 2-5 mm size and different shapes. 

In a laboratory size treatment plant, it is required to pump the sewage (a) sludge through a bed of porcelain spheres packed in a 50 mm diameter... 

The theoretical bases concerning mass transfer operations have been available in chemical engineering texts for many years and will not be developed further in this book. Rather, this book provides procedures for designing packed columns based on practical experiences acquired over 40 years that have produced satisfactory column performance. In many commercial situations, the application of rigorous theory is difficult because of the lack of sufficient data on physical or chemical properties. In addition, information on the desired operation may be available only from very small or laboratory-size columns with the resultant problems of scale-up. The empirical design methods presented in this book, in many cases, have been developed as a result of modifications to increase the capacity or efficiency of previously operating columns. These same methods also have been used to design new columns in similar services. 

The elution of such gels is an example not of size exclusion but rather of hydrodynamic fractionation (HDF). However, it must be remembered that merely being able to physically fit an insoluble material through the column interstices is not the only criterion for whether the GPC/HDF analysis of an insoluble material will be successful. A well-designed HDF packing and eluant combination will often elute up to the estimated radius in Eq. (5), but adsorption can drastically limit this upper analysis radius. For example, work in our laboratory using an 8-mm-bead-diameter Polymer Laboratories aqueous GPC column for HDF found that that column could not elute 204 nM pSty particles, even though Eq. (5) estimates a critical radius of —1.5 jam. 

The value for is conservatively interpreted as the particle diameter. This is a perfectly feasible size for use in a laboratory reactor. Due to pressure-drop limitations, it is too small for a full-scale packed bed. However, even smaller catalyst particles, dp 50 yum, are used in fluidized-bed reactors. For such small particles we can assume rj=l, even for the 3-nm pore diameters found in some cracking catalysts. 

Factors re.sponsible for the occurrence of scale-up effects can be either material factors or size/shape factors. In addition, differences in the mode of operation (batch or semibatch reactor in the laboratory and continuous reactor on the full scale), or the type of equipment (e.g. stirred-tank reactor in the laboratory and packed- or plate- column reactor in commercial unit) can be causes of unexpected scale-up effects. A simple misuse of available tools and information also can lead to wrong effects. 

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